Questions tagged [dapps]

Questions about applications and projects on Ethereum: a decentralized application (dapp) does not require any servers or backends and runs independent on a distributed blockchain.

164 questions with no upvoted or accepted answers
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6
votes
5answers
1k views

When would it make sense to use node server for an application using smart contracts?

I am wondering if there are example cases where it would make sense to use a typical Node.js client-server app where the blockchain node would be running on the server. At first glance, this would ...
5
votes
0answers
644 views

Verify the ownership of an ethereum account

I have built a web game where users can purchase virtual items for their avatar with tokens obtained during an ICO. What is the best solution for delivering the items to the correct web game user? I ...
4
votes
0answers
255 views

Truffle hangs forever with parity with PoA

I'm trying to create a private chain using parity (PoA) and truffle but when I do truffle migrate it hangs forever with the following output: > [ > { > "jsonrpc": "2.0", &...
4
votes
0answers
108 views

Querystring in Parity Dapp frontend

I'm playing with local Dapp for Parity. When I'm trying to use query string in Dapp, I can't get it with js: I see that iframe is used inside, but have no idea, how to add query string there. Is ...
3
votes
0answers
115 views

Evaluation of DApp (Smart Contract) storage concept with IPFS

i hope you can help me improve or validate my storage concept. I am glad for each suggestion. Since this is my first DApp, i might not consider all possible options for my problem. To understand the ...
3
votes
1answer
59 views

How to let uses select their account?

I am quite confusued on how users should select the account they want to use with dapps. Before version 0.9.0 of mist I could just use web3.eth.accounts[0] and let users select what account they want ...
3
votes
0answers
56 views

EVM Invalid JUMP when using webpack app

I am creating a frontend app based on Truffle + Webpack, following this tuto : http://truffleframework.com/tutorials/building-testing-frontend-app-truffle-3, and have no uderstanding of JavaScript at ...
3
votes
0answers
48 views

Casting Object to BigNumber in Meteor DAPPs

Web3 incorporates the BigNumber library in order to handle 256bit numbers. I'm finding this problematic in Meteor as most of Meteor's reactive storage schemes such as Session, ReactiveDict and ...
3
votes
0answers
516 views

Pyethapp Build error: No files/directories in ..pip-build-gpzcs1\leveldb\pip-egg-info (fr om PKG-INFO)

I'm new to ethereum & do not have any ethereum clients 'installed'. I'm trying to install pyethapp in a clean virtualenv following the github tutorial, but it produces the following error. ...
2
votes
0answers
42 views

Android Studio And Ethereum?

how i can connect android studio application with Ganache? i'm trying to build an application on android (that is my Front end) with a Smart contract (Back end) on my private Blockchain (Ganache). it'...
2
votes
0answers
27 views

How shoud I properly initialize DApp and get account address?

I am writing DApp in react, and basically I want to initialize web3, unlock account, and display it. Having web3 in my package.json In the onload I've tried to go following: let Web3 = require('web3')...
2
votes
0answers
131 views

How to implement percentage deposit function to smart contract

I need to implement on the deposit function when the ownerAddress is doing a deposit a 10% to be freeze in the smart contract and and if the ownerAddress want's to call the returnDeposit function by ...
2
votes
1answer
23 views

One general contract for all or spawn new one for each instance?

What be the advantages vs. disadvantages or running a general contract or spawning a new one for each instance. Let say, that I am providing a contract so people can create their own crowdfunding. ...
2
votes
0answers
683 views

web3.personal.newAccount() successfully created but not listed in ganache accounts.why?

I am using truffle framework for Dapp development and I am new in Blockchain.I used the command web3.personal.newAccount() to create a new account. But i cannot view this account when i take ...
2
votes
1answer
216 views

Calling function from another contract reverts

I've been developing a dApp that needs ERC721 tokens. I have three contracts, a base contract, the one to mint tokens and another one for auctions. The inheritance looks like Base > Token > Auctions. ...
2
votes
0answers
185 views

Decentralized File Storage on Ethereum white paper

I am reading white paper of Ethereum, and I am confused by this example of the Section. Decentralized File Storage, which is part of the Section. Applications: The key underpinning piece of such a ...
2
votes
1answer
217 views

Which ethereum dapps are 100% decentralized and not semi-decentralized (centralized)?

Correct me if I'm wrong here, but I see dapps as independent solo code that you can download to you computer and it interacts with the Ethereum blockchain. Looking at crypto kitties, you have to ...
2
votes
2answers
175 views

Mining, Ethers and Private Blockchain DAPPs

I am building a private Blockchain cluster DAPP envisaged to have 5 to 10 parties owning their own nodes (or node clusters). At this moment, there is no specific mandate to incentivize miners, though ...
2
votes
0answers
573 views

What is the best practice of a Dapp development mixed with Python/Django?

I've written and tested the Smart Contracts in Truffle, and now want to develop a front-end and a small back-end for my Dapp. So far, I preferred MVP frameworks, particularly Django. Therefore, what ...
2
votes
1answer
191 views

Can i delete some old files inside chaindata folder?

I am running geth with fast sync, Can i delete some old files inside chaindata folder so that my ssd will have some empty space or it will create some problems ?
2
votes
1answer
193 views

How do I get access to uPort from a mobile Browser

I've developed a simple DApp that uses uPort and it works fine on Desktop - where I can login through uPort with the QR Code. On a mobile browser (Anrdoid Chrome) I'm auto directed to uPort where it ...
2
votes
0answers
390 views

Send transaction with metamask and web3

I'm new to the topic but can I somehow sendTransaction via contract instance? What I'm missing here? I simply want to send some ether to contract. var abi =[ { "constant": true, "...
2
votes
2answers
123 views

Possible to search swarm or blockchain?

I'm getting my feet wet in this blockchain world and looking to build a dapp based on Ethereum for maintaining an inventory of products. About 400,000 items that can be updated, removed or added to by ...
2
votes
0answers
52 views

show specific information to specific users in meteor dapp

if a have a dapp with different users, and each user has his/her own profile page they can log in to. On this profile page, the user should be able to change/add his user information (name, age, etc) ...
2
votes
0answers
34 views

How to return form data from an EthElements.Modal.question?

I'm trying to process data from an EthElements.Modal.question, however no event is passed when OK is clicked and this just points to the model call data and not the Template content.
2
votes
0answers
62 views

Why does Mist doest show up anything for me running on testnet

I just see a blank screen when I open Mist Browser on ubuntu running on testnet. What is the issue ? I couldnt start in the first place. But after using --ignore-gpu-blacklist I could start, Then I ...
1
vote
1answer
23 views

Both web3.eth.accounts.create() and web3.eth.personal.newAccount() not working

I'm making a dApp on reactjs. I wanted to create a new account and have done it trying 2 methods this.web3.eth.personal.newAccount() this.web3.eth.accounts.create() I have attached the code below(...
1
vote
1answer
75 views

How to call a contract function that alters blockchain state on geth console

It should be easy, but I'm having a hard time using a simple smart contract described in the Solidity language reference called SimpleStorage. It only as one attribute, a setter and a getter, and I'm ...
1
vote
0answers
58 views

How to use web3-react with truffle Dapp? any sample code / tutorial?

I am new to react and finding issues with the front-end of the Dapp application. Especially in web3 version > web3 1.0.0 I just heard about the web3-react and I think it will be a lot easier. I ...
1
vote
2answers
52 views

Storage/Retrieval of mapped structure data

I want to store the structure data in a mapping i.e. if I have a student structure as described below, then I should be able to have a myriad of students and distinguish between them using wallet ...
1
vote
1answer
48 views

how to securely share digital asset in a fully decentralized DApp

I want to design a proof of concept of a fully decentralized secure asset sharing DApp. Seller uploads the asset they want to share with a price and buyer pays it with ether or a token. Frontend and ...
1
vote
0answers
28 views

Transaction included in block whereas log not generated

When I sent a transaction continuously below 27 Transaction Per Second (TPS) then all transaction is included in a block and generated the log as expected. Whereas When TPS increases above 27 then ...
1
vote
0answers
19 views

Transaction sent from web3 cannot reached all transaction to network node

I used one node endpoint to interact with the network. While sending a transaction from web3.js 0.20 to ethereum network, transaction per second (TPS) I achieved is only 28 TPS. I have configured the ...
1
vote
1answer
206 views

Empty value (0x) returned from contract web3j

I'm trying to deploy a very simple contract on Windows 10, using Web3j 4.2.0. I've created an account using Mist. I've set up one local ethereum node (using geth) on my machine and I'm able to deploy ...
1
vote
0answers
82 views

sendTransaction never resolves on web3.js 1.0.0 beta49 - beta52

My plain vanilla sendTransaction doesn't ever resolve on ganache with web3js 1.0.0 beta52: async function sendTx() { const receipt = await web3.eth .sendTransaction({ to: "0x1...", ...
1
vote
2answers
420 views

How can I return dynamic string array in Solidity?

How can I return a dynamic string array? I came across serialization and deserialization. How can I serialize and deserialize dynamic string array ? pragma solidity ^0.5.0; contract Abc{ string[]...
1
vote
0answers
27 views

Smart Contract ABI in Remix (Ethereum)

When I deploy smart contract on the Rinkeby network using Remix the ABI of smart contract does not contain its address, so how do I connect it with my frontend application.
1
vote
2answers
316 views

Uploading files on IPFS Infura

I am trying to make a dapp to upload files on IPFS Infura. I am using IpfsHttpClient in web browser by including the script <script src="https://unpkg.com/ipfs-http-client/dist/index.min.js">&...
1
vote
0answers
85 views

No contract code at give address

Its a bit of a long question... I am using Go to deploy a Smart Contract using the following code: client, err := ethclient.Dial("http://localhost:8545") if err != nil { errorhandler.HandleErr(...
1
vote
1answer
50 views

Ethereum with Rails

I am much familiar with Rails but new in the Ethereum. But base on my understanding, if I am going to build a Dapp. The web stack should not include the back-end system like Rails. But why there's so ...
1
vote
1answer
77 views

Design Dapp with Kotlin front end

To develop Dapp using Kotlin programming language for the front end design, Where should I place this code? and what it should be changed? <script> // Connect a the web3 provider ...
1
vote
0answers
11 views

Can I expose a dapp via whisper ?

I have a question regarding the possibility and probably the steps to do in order to be able to export my App via the whisper protocol. how to do it and in which case it can be better than other ...
1
vote
0answers
23 views

Our vendor created the IPFS and Ethereum platform to store the PDF documents. How do i use the same code in Desktop Application

I am a quiet layman in IPFS and Ethereum. Our vendor created the web application which stores the documents IN IPFS (Ethereum). Now, we do need to do the same in the desktop application also. ...
1
vote
1answer
52 views

Deployed Smart contract methods are not updating the value when restart the geth instance.Why?

Started Geth using following command geth --identity "testpvtnode" --rpc --rpcport "8545" --rpccorsdomain "*" --datadir <pvtnetdatapath> --port "30303" --rpcapi db,eth,net,web3,personal --...
1
vote
2answers
121 views

How to use fiat exchange rate oracle in DAPP?

my team is trying to develop a DAPP about fiat exchange rate. How to get the latest fiat exchange rate (USD/EURO etc.) accurately from external Oracles(Or are there better ways doing this)?
1
vote
1answer
245 views

Why no dapps in the Google Play Store? Why Ethereum not accessible by default in smartphone?

Before I create a decentralized application, I want to know whether it already exists. I thought the first step would be to search the Google Play Store, but it appears dapps are not available on the ...
1
vote
0answers
24 views

Is it possible to deploy Dapp on Ethereum classic network and be listed in mist?

So as a small bisness entety can not pay 100k USD for app deployment, one wonders on is it possible to deploy Dapp not in the test net but in a more real ETC one?
1
vote
0answers
24 views

trading a secret message with some person only after money is paid

I want to build a DAPP where person A trades a message with person B for ether. Since the message is secret, person A encrypts the message by using public key of person B and stores the message in ...
1
vote
0answers
54 views

import packages in petdapp

I unboxed petdapp and done some editing where I need to import bcrypt-nodejs in app.js and used following steps. npm install bcrypt-nodejs --save npm install require --save app.js var bcrypt = ...
1
vote
1answer
55 views

MetaMask transaction popup opens on another computer

We have two computers on the same local network with Static IP for internet. When Computer A calls a transaction through a DApp for an address X, Computer B Metamask is also getting triggered with the ...